Stem Xylem as a Possible Pathway for Mineral Retranslocation From Senescing Leaves to the Ear in Wheat

1982 ◽  
Vol 9 (2) ◽  
pp. 197 ◽  
Author(s):  
P Martin
Keyword(s):  
Time Course ◽  
Flag Leaf ◽  
Triticum Aestivum L ◽  
Mineral Nutrients ◽  
Potassium Transport ◽  
Short Term ◽  
Plant Parts ◽  
Vegetative Plant ◽  
Nitrogen Retranslocation ◽  
Nitrogen Phosphorus

Retranslocation of mineral nutrients in wheat (Triticum aestivum L. cv. Kolibri) during the development phase from 19-22 days post-anthesis to maturity was investigated in isolated culms (with three leaves attached). From the amounts present in leaves and stem at the time when the culms were detached, 75% nitrogen, 86% phosphorus, 22% potassium, and 37% magnesium were retranslocated from vegetative plant parts to the ear. No calcium was retranslocated from the leaves, but up to 27% calcium in the stem was relocated. Steam girdling of the stem between the flag leaf and the ear did not change the amounts of nitrogen, phosphorus and magnesium retranslocated and transported to the ear but reduced calcium movement slightly. Potassium transport to the ear was, however, almost completely inhibited by the phloem discontinuity induced by steam girdling. The results for nitrogen and potassium were confirmed in short-term experiments (24-48 h) using 15N and 86Rb. In a comparison between girdled culms, it was found that removal or shading of the ear decreased nitrogen retranslocation from the leaves and delayed the time course of leaf senescence. The results show that a continuous connection by sieve elements between leaves as source and grains as sink in wheat is not a prerequisite for retranslocation of nitrogen, phosphorus or magnesium.

ESTIMATION OF PROTEIN CONCENTRATION IN THREE PLANT PARTS AT FOUR GROWTH STAGES IN WHEAT BY NEAR INFRARED REFLECTANCE

1988 ◽  
Vol 68 (1) ◽  
pp. 217-220 ◽  
Author(s):  
M. M. NOAMAN ◽  
G. A. TAYLOR ◽  
C. F. MCGUIRE
Keyword(s):  
Triticum Aestivum ◽  
Protein Concentration ◽  
Near Infrared ◽  
Flag Leaf ◽  
Genotypic Variation ◽  
Triticum Aestivum L ◽  
Growth Stages ◽  
Infrared Reflectance ◽  
Near Infrared Reflectance ◽  
Plant Parts

Near Infrared Reflectance was examined to be used as a technique of estimating protein concentration in the head, flag leaf, and peduncle of Newana, hard red spring wheat (Triticum aestivum L.) at four growth stages. The plant samples were taken from a field experiment including three N levels. The standard Kjeldahl method was used to estimate protein concentration in these plant parts. Protein concentration in these samples ranged from 2.7% in the peduncle to 16.7% in the flag leaf. The NIR was calibrated using these plant parts. Using 3 of 19 available filters the R2 for the calibration between Kjeldahl and NIR was 0.98. The validity of the NIR calibration was tested using an independent set of plant parts of winter wheat taken at three growth stages. The r2 obtained between Kjeldahl and NIR was highly significant. It was concluded that NIR provides an accurate, rapid, and economical technique for estimating protein concentration in aerial plant tissues. This should facilitate the screening of wheats for genotypic variation in aerial plant protein.Key words: Wheat, Kjeldahl N, protein translocation, protein estimation, Triticum aestivum L.

scholarly journals Effects of plant density and nitrogen fertilization in winter wheat (Triticum aestivum L.). 2. Incidence of Gerlachia nivalis and Fusarium spp. related to yield losses.

1987 ◽  
Vol 35 (2) ◽  
pp. 155-162
Author(s):  
J. Ellen ◽  
C.J. Langerak
Keyword(s):  
Plant Density ◽  
Triticum Aestivum L ◽  
Yield Losses ◽  
Fusarium Spp ◽  
Severe Attack ◽  
Plant Parts ◽  
Vegetative Plant ◽  
High Plant Density ◽  
Gerlachia Nivalis ◽  
Time Of Harvest

At the low plant density there was more infection by G. [Monographella] nivalis and F. spp. than at the high plant density. In the post-floral period this effect was reflected in a more severe attack of the vegetative plant parts and a greater number of grains being infected at the time of harvest. Delaying the first N dressing and/or the supplementary nitrogen fertilizations at a later stage in the growing season enhanced attack by M. nivalis and F. spp. M. nivalis was the most important; 75% of the attacked grains were infected by it. It is concluded that seed producers should apply nitrogen only in the early stages of plant development, which may reduce considerably the transmission of these pathogens to the new seeds. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Short-term volume and turgor regulation in yeast

2008 ◽  
Vol 45 ◽  
pp. 147-160 ◽  
Author(s):  
Jörg Schaber ◽  
Edda Klipp
Keyword(s):  
Dynamic Model ◽  
Volume Change ◽  
Volume Regulation ◽  
Time Course ◽  
Osmotic Shock ◽  
Intracellular Concentration ◽  
Short Term ◽  
Hydrodynamic Property ◽  
Turgor Regulation ◽  
Thermodynamic Framework

Volume is a highly regulated property of cells, because it critically affects intracellular concentration. In the present chapter, we focus on the short-term volume regulation in yeast as a consequence of a shift in extracellular osmotic conditions. We review a basic thermodynamic framework to model volume and solute flows. In addition, we try to select a model for turgor, which is an important hydrodynamic property, especially in walled cells. Finally, we demonstrate the validity of the presented approach by fitting the dynamic model to a time course of volume change upon osmotic shock in yeast.

Morphological Changes in the Brain of Acutely Ill and Weight-Recovered Patients with Anorexia Nervosa

2014 ◽  
Vol 42 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Jochen Seitz ◽  
Katharina Bühren ◽  
Georg G. von Polier ◽  
Nicole Heussen ◽  
Beate Herpertz-Dahlmann ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Cognitive Deficits ◽  
Time Course ◽  
Morphological Changes ◽  
Meta Analysis ◽  
Short Term ◽  
Clinical Prognosis ◽  
Qualitative Review ◽  
Brain Changes ◽  
The Brain

Objective: Acute anorexia nervosa (AN) leads to reduced gray (GM) and white matter (WM) volume in the brain, which however improves again upon restoration of weight. Yet little is known about the extent and clinical correlates of these brain changes, nor do we know much about the time-course and completeness of their recovery. Methods: We conducted a meta-analysis and a qualitative review of all magnetic resonance imaging studies involving volume analyses of the brain in both acute and recovered AN. Results: We identified structural neuroimaging studies with a total of 214 acute AN patients and 177 weight-recovered AN patients. In acute AN, GM was reduced by 5.6% and WM by 3.8% compared to healthy controls (HC). Short-term weight recovery 2–5 months after admission resulted in restitution of about half of the GM aberrations and almost full WM recovery. After 2–8 years of remission GM and WM were nearly normalized, and differences to HC (GM: –1.0%, WM: –0.7%) were no longer significant, although small residual changes could not be ruled out. In the qualitative review some studies found GM volume loss to be associated with cognitive deficits and clinical prognosis. Conclusions: GM and WM were strongly reduced in acute AN. The completeness of brain volume rehabilitation remained equivocal.

Spikelet fertility and heat shock transcription factor (Hsf) gene responses to heat stress in tolerant and susceptible rice (Oryza sativa L.) genotypes

2019 ◽  
Vol 157 (04) ◽  
pp. 283-299 ◽  
Author(s):  
C. Malumpong ◽  
S. Cheabu ◽  
C. Mongkolsiriwatana ◽  
W. Detpittayanan ◽  
A. Vanavichit
Keyword(s):  
Heat Stress ◽  
Pollen Germination ◽  
Seed Set ◽  
Oryza Sativa L ◽  
Flag Leaf ◽  
Pollen Viability ◽  
Spikelet Fertility ◽  
Anther Dehiscence ◽  
Spikelet Sterility ◽  
Plant Parts

AbstractThe reproductive stage of rice is the most sensitive to heat stress, which can lead to spikelet sterility. Thus, heat-tolerant and heat-susceptible genotypes were used to investigate their differences in terms of phenotypic responses and expression changes of Hsf genes at the pre-flowering stage under heat stress. Results clearly showed that panicles had the highest temperature compared with other plant parts under both natural and heated conditions. However, the temperatures of tolerant and susceptible genotypes were not significantly different. In terms of spikelet fertility, the tolerant lines M9962 and M7988 had high seed set because their anther dehiscence, pollen viability and pollen germination were only slightly affected. In contrast, the susceptible line Sinlek showed severe effects at all steps of fertilization, and the pollen viability of M7766 was slightly affected under heat stress but was more affected in terms of anther dehiscence and pollen germination. Both susceptible lines showed dramatically decreased seed set. In addition, the expression of six HsfA genes in the flag leaves and spikelets at the R2 stage of plants under heat stress showed different responses. Notably, expression of the HsfA2a gene was predominantly upregulated in the flag leaf and spikelets under heat stress in M9962. Therefore, it can be concluded that heat stress has severe effects on the stamen, and that different genotypes have different susceptibilities to heat stress.

In situ studies on alginic acid synthesis and other aspects of the metabolism of Laminaria digitata

1972 ◽  
Vol 50 (1) ◽  
pp. 177-184 ◽  
Author(s):  
Johan A. Hellebust ◽  
Arne Haug
Keyword(s):  
Amino Acids ◽  
Time Course ◽  
Alginic Acid ◽  
Acid Synthesis ◽  
Short Term ◽  
Fresh Weight Basis ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Rate Of Photosynthesis

Amino acids, particularly alanine and aspartate, become more strongly labeled than mannitol in short-term 14C-photoassimilation experiments. The amino acids are the most likely sources of carbon for alginic acid synthesis and respiration in the dark, in contrast to mannitol, which appears to be relatively unavailable. Temperature is very important in determining the rate of loss of recent photoassimilate in L. digitata. The rate of photosynthesis, on a fresh weight basis, is much higher for blades than for stipes.The time course for incorporation of photoassimilated carbon into alginate differs for the stipe and blade both in light and dark periods. Very little 14C enters alginate in blades in the dark, while alginate in stipes acquires considerable amounts of activity during dark periods. Alginate in both blade and stipe acquires 14C predominantly in mannuronic acid residues of their alginate during short-term photoassimilation periods, while guluronic acid residues become relatively more rapidly labeled during dark periods.

scholarly journals Short-Term Treadmill Running as a Model for Studying Cell-Free DNA Kinetics In Vivo

2011 ◽  
Vol 57 (4) ◽  
pp. 633-636 ◽  
Author(s):  
Thomas Beiter ◽  
Annunziata Fragasso ◽  
Jens Hudemann ◽  
Andreas M Nieß ◽  
Perikles Simon
Keyword(s):  
Time Course ◽  
Treadmill Exercise ◽  
Plasma Concentrations ◽  
High Mobility ◽  
Treadmill Running ◽  
Short Term ◽  
Cell Free Dna ◽  
Free Dna ◽  
Cross Country

BACKGROUND Increased plasma concentrations of cell-free DNA (cf-DNA) are considered a hallmark of various clinical conditions. Despite intensive research in this field, limited data are available concerning the time course of release and clearance of cf-DNA in vivo. METHODS We extracted cf-DNA from plasma samples taken before and immediately after a 10-km cross-country run, and from samples taken before, immediately after, and 30 min after exhaustive short-term treadmill exercise. The contribution of nuclear (nDNA) and mitochondrial DNA (mtDNA) was measured by quantitative real-time PCR. The incremental treadmill exercise setup was exploited to delineate the precise sequencing and timing of cf-nDNA, lactate, and high-mobility group box 1 protein (HMGB1) release during the exercise and recovery phases. RESULTS Postexercise plasma cf-nDNA concentrations in cross-country and treadmill runners were significantly increased, by 7.6-fold and 9.9-fold, respectively (P < 0.001). cf-nDNA concentrations were not correlated with age, sex, or body mass index. Plasma concentrations of cf-nDNA and HMGB1 in postexercise samples of treadmill runners were significantly correlated (r = 0.84; P = 0.004). cf-mtDNA concentrations were not affected by treadmill exercise. Time-course analyses demonstrated that cf-nDNA is released within minutes after the onset of exercise and is rapidly cleared from the circulation after the cessation of exercise. Nearly congruent kinetics for cf-nDNA, lactate, and HMGB1 were observed during the exercise phase. CONCLUSIONS A single bout of exhaustive short-term treadmill exercise constitutes a versatile model system suitable for addressing basic questions about cf-DNA biology.

Photosynthesis, translocation, and alginic acid synthesis in Laminaria digitata and Laminaria hyperborea

1972 ◽  
Vol 50 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Johan A. Hellebust ◽  
Arne Haug
Keyword(s):  
Time Course ◽  
Alginic Acid ◽  
Acid Synthesis ◽  
Laminaria Hyperborea ◽  
Short Term ◽  
Fresh Weight Basis ◽  
Mannuronic Acid ◽  
Guluronic Acid ◽  
Isolated Cortex ◽  
Photosynthetic Capacities

New and old tissues of L. digitata blades have very similar photosynthetic capacities on a fresh weight basis. Very little of the photoassimilate goes into alginic acid, or other macromolecular substances in old blade tissues. Less than 1% of the photoassimilated 14C in the old blade portion of a L. digitata blade was translocated to the new blade tissues in a 5-h experiment. In contrast, there is rapid transport of photoassimilate from bark cells to cells of the underlying tissues of L. digitata and L. hyperborea stipe sections. Isolated cortex and medulla tissues of L. digitata stipes have significant photosynthetic capacities, but are probably so strongly shaded by the darkly pigmented bark cells that little photosynthesis can normally occur in these tissues.A larger proportion of the photoassimilated carbon enters alginate in the cortex and medulla than in the bark of L. digitata and L. hyperborea stipes in short-term experiments. The time course for incorporation of photosynthate into alginate in continuous and pulse-labeling experiments indicates the presence of relatively large pools of alginate precursors. A large proportion of the total 14C incorporated into alginate in short-term experiments is found in the "M–M" (mannuronic acid) and "M–G" (alternating mannuronic and guluronic acid) block components.

Recovery from Adaptation to Moving Gratings

Perception ◽  
1977 ◽  
Vol 6 (6) ◽  
pp. 719-725 ◽  
Author(s):  
Max J Keck ◽  
Benjamin Pentz
Keyword(s):  
Time Course ◽  
Spontaneous Recovery ◽  
Motion Aftereffect ◽  
Time Decay ◽  
Short Term ◽  
Test Grating ◽  
Test Conditions ◽  
Sinusoidal Gratings ◽  
Short Term Adaptation

Short-term adaptation to moving sinusoidal gratings results in a motion aftereffect which decays in time. The time decay of the motion aftereffect has been measured psychophysically, and it is found to depend on (i) the spontaneous recovery from the adapted state, and (ii) the contrast of the test grating. We have measured the decays for various test conditions. An extrapolation of the measurements allows us to obtain a decay which represents the time course of the spontaneous recovery of the direction-sensitive mechanisms.

Characteristics of the canopy, root system and grain yield of a crop of Lupinus angustifolius cv. Unicrop

1975 ◽  
Vol 26 (3) ◽  
pp. 497 ◽  
Author(s):  
EAN Greenwood ◽  
P Farrington ◽  
JD Beresford
Keyword(s):  
Carbon Dioxide ◽  
Grain Yield ◽  
Leaf Area ◽  
Time Course ◽  
Dry Weight ◽  
Grain Filling ◽  
Main Axis ◽  
Carbon Dioxide Exchange ◽  
Area Index ◽  
Plant Parts

The time course of development of a lupin crop was studied at Bakers Hill, Western Australia. The aim was to gain insight into the crop factors influencing yield. Weekly measurements were made of numbers and weights of plant parts, and profiles of roots, leaf area and light interception. A profile of carbon dioxide in the crop atmosphere was taken at the time of maximum leaf area, and the net carbon dioxide exchange (NCE) of pods was estimated for three successive weeks. The crop took 10 weeks to attain a leaf area index (LAI) of 1 and a further 9 weeks to reach a maximum LAI of 3.75, at which time only 33% of daylight reached the pods on the main axis. Once the maximum LAI was attained at week 19, leaf fall accelerated and rapid grain filling commenced almost simultaneously on all of the three orders of axes which had formed pods. Measurements of NCE between pods on the main axis and the air suggest that the assimilation of external carbon dioxide by the pods contributed little to grain filling. Grain dry weight was 2100 kg ha-1 of which 30%, 60% and 10% came from the main axis, first and second order apical axes respectively. Only 23% of the flowers set pods and this constitutes an important physiological limitation to grain yield.

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